This invention relates to an apparatus and method for continuously monitoring the concentration of a compound which exhibits circular dichroism activity and is contained in a flowing solution also containing a plurality of other compounds in solution.
In industrial processes, it is frequently desired to monitor the concentration of a subject compound which is present in a flowing solution stream containing a plurality of compounds. Further, it is frequently desired that the concentration of the subject compound will be monitored continuously so that the concentration of that compound in the flowing solution stream that is passing the monitor will always be known. The apparatus and method selected for monitoring the concentration of the subject compound depends in part on the chemical or physical characteristics of that compound and in part on the nature and characteristics of the industrial process of which the flowing solution stream is a part.
Depending upon the characteristics of the subject compound, the concentration of that compound might be determined by chemical methods such as high pressure liquid chromatography, gas chromatography, spectrophotometry, or, if the subject compound exhibits circular dichroism activity, by measurement using circular dichroism spectropolarimetry.
Compounds which exhibit circular dichroism activity are those which contain a chiral center in the molecule and which absorb ultraviolet or other electromagnetic radiation. This includes many molecules which are active in biological processes.
As it is presently known to perform circular dichroism spectropolarimetry to monitor the concentration of a compound in a flowing solution, a small volume of sample must first be isolated from the flowing solution stream before analysis of the concentration of the subject compound in a circular dichroism spectropolarimeter can be performed.
A significant problem is that the isolation of the small volume of sample and the execution of the circular dichroism analysis are time consuming and require a significant amount of handling of the sample. Use of more than several minutes to make the concentration determination can negate the effectiveness of the method as a process monitor. This is because the point in the flowing solution stream from which the sample was taken will be too far downstream by the time the concentration of the subject compound in the sample is known. Further, where the flowing solution stream is maintained under extreme conditions of temperature or pressure, isolating a sample is made prohibitively difficult and altering the conditions of the sample to allow for handling can alter or destroy the integrity of the compounds in the sample. Thus, as presently performed, circular dichroism spectropolarimetry apparatus and methods may be prohibited for monitoring the concentration of compounds in some flowing sample streams.
It is, therefore, the object of this invention to provide an apparatus and method for using circular dichroism spectropolarimetry to continuously monitor the concentration of a subject compound which exhibits circular dichroism activity in flowing solution streams without having to remove a sample of the solution from the flowing stream.
It is the further object of this invention to provide an apparatus and method capable of continuously monitoring the concentration of a subject compound in a flowing solution stream where the solution stream is maintained under extreme conditions of temperature and pressure.